The new study of the jaw confirms that the "first Europeans" arrived well over a million years ago, reports the archaeological team—led by Eudald Carbonell of the Rovira i Virgili University in Tarragona, Spain—in the latest issue of the journal Nature.

The jaw's owner has been labeled a Homo antecessor—a species first named in 1997 based on other human fossils found at Atapuerca. The sex isn't known, but the new human was likely aged between 30 and 40 at the time of death.

"Since we now know those [1997] fossils date to 900,000 [years ago], the time difference is not great, and, provisionally at least, I think it's logical to assign the mandible to Homo antecessor," said dig co-director José Maria Bermúdez de Castro of the National Research Center on Human Evolution in Burgos, Spain.

The new findings suggest that H. antecessor was most probably unique to Europe, the researchers say.

Bone Breakers

The lower jawbone was discovered inside a 60-foot-long (18-meter-long) cave known as Sima del Elefante. The region was originally exposed by a railway cutting through a limestone area rich in early hominin, or human, and animal remains.

The complex of fossils allowed scientists to use a variety of methods to confirm the age of the fossils, including magnetic analysis, radioactive dating, and geologic studies of the clustered bones and artifacts—a necessity because the dating of human fossils remains a controversial area of research.

For example, 32 stone flints also excavated from the cave date to the same age as the fossils, according to Bermúdez de Castro said.

The flints include simple tools that were likely used by the early humans to hack up mammal carcasses and get at bone marrow, as evidenced by cut marks found on nearby limb bones belonging to unidentified herbivores.